1. Prepare angel food cake according to label directions. Suspend and cool cake according to directions; remove from pan. Cut horizontally in half. Reserve top half for dessert; wrap and freeze bottom half for later use.
2. Drain juice from pineapple rings into small saucepan. Sprinkle gelatin over juice; let stand for 5 minutes to soften. Place over very low heat just until gelatin is dissolved.
3. Arrange pineapple rings on bottom of clean angel cake pan. Cut cherries in half and arrange between pineapple rings. Pour in gelatin mixture; chill until semi-set, about 20 to 30 minutes.
4. Place angel food cake in pan, pressing lightly into semi-set gelatin mixture. Chill until completely set, about 1 1/2 hours. Dip pan quickly in hot water and unmold cake on serving platter.